Tagged Salmon

The Idaho Department of Fish and Game, the U.S. Fish and Wildlife Service, and the Nez Perce Tribe annually PIT ag more than 200,000 Spring/Summer Chinoook Salmon smolts released from Idaho hatcheries in the Clearwater, Snake, and Salmon rivers. PIT (passive integrated transponder) tags smaller than a grain of rice are inserted into the body cavity of smolts where they remain there throughout the life of the fish. Each PIT tag generates a unique weak electrictronic signal when subjected to a magnetic field and that signal can be detected by special arrays of antenas installed in fish passage facilities at Bonneville Dam , two other in Columbia River dams and two Snake River dams (Ice Harbor and Lower Granite). Since each PIT tag emits a unique signal and we know which tags were applied at each hatchery we can identify which hatchery returning tagged adult fish are from as they pass over dams where detectors are installed. Since we know the ratio of tagged smolts to untagged smolts from each hatchery release. we can estimate the number of untagged fish from a hatchery that are swimming by a dam as well. For example, if we tagged one smolt per every 50 smolts released at a hatchery, then each tag detected among adult returns from that hatchery equates to 50 fish. For the 2014 adult salmon return we presently have enough PIT tag detections from Bonneville Dam to safely say that spring Chinook returns destined for the hatcheries in the Clearwater, Snake, and Rapid rivers are at or slightly above the pre-season forecasts for those hatcheries. Based on tag detections to date our preliminary estimates of the numbers of adult salmon available for harvest in non-tribal sport fisheries are:  about 4,500 fish in the Clearwater River drainage, about 1,000 in the Snake River below Hells Canyon, and about 5,000 in the Lower Salmon/Little Salmon River fishery. Because returns to the South Fork Salmon River and the Upper Salmon River haver later run timing we do not have sufficient tag detections at this time to make inseason run size projections for hatcery returns to those areas. The Idaho Fish and Game Commission will meet mid-May to set seasons for salmon returns to those areas.